The present proposal represents a comprehensive multidisciplinary approach to the study of prenatal exposure to delta-9- tetrahydrocannabinol (THC) using the laboratory rat. Four experienced investigators in the fields of developmental toxicology/teratology, developmental psychobiology, developmental nutrition, and cannabinoid pharmacology will study a wide range of developmental outcomes resulting from prenatal exposure to THC. These studies represent a logical progression in a research program initiated in 4/83 and include the effects of prenatal THC on the following outcomes: 1) the study of in utero and perinatal female lethality to determine the developmental period when death occurs, 2) dose-response studies to better describe delayed growth and catch-up, 3) pharmacological studies of the postnatal persistence of THC in a variety of offspring tissues and possible correlation with growth inhibition, 4) measures of milk consumption and suckling efficiency and their relationship to growth, 5) studies of qualitative changes in body composition durign postnatal growth, and 6) possible long-term effects in adult offspring including a) locomotor activity with and without amphetamine challenge and b) reflex startle with and without THC challenge. We hope the results of this programmatic research will increase our knowledge of the developmental toxicity of THC during pregnancy and provide useful scientific information with respect to the prenatal hazard of THC exposure in the human population.